Ventilation system in summer?

  • Erstellt am 2017-05-19 13:52:04

Alex85

2017-05-31 01:56:15
  • #1

Due to the lack of linking options, I can only say that the information comes from their website.
And yes, they are all just typical manufacturer specifications under some lab conditions, I assume. But if everyone is cheating, then they are comparable again, as long as they all cheat more or less equally well.

I mean the enthalpy heat exchanger performs the described balancing, but also discharges the excess water when the membrane saturates. Correct? Then it should help against excessively humid air.
 

andimann

2017-05-31 09:56:08
  • #2
Hello,

that would be nice:



first of all, I wouldn’t be sure whether the membrane lets water molecules through equally in both directions, there are definitely membranes that work like a one-way street.

Then, such a thing only works up to equilibrium. With tricks in the heat exchanger design, you can shift the equilibrium a bit
but not to the extent that water would nicely accumulate in the exhaust air while the supply air remains dry.

And the vapor pressures would also have to be quite similar. The outside air is about 20 °C at 60-70 % relative humidity and the exhaust air is 23.5 °C at 50-55 % relative humidity. I don’t have time to calculate it in detail right now but there aren’t worlds of difference.

As I said, such an enthalpy exchanger is meant to balance extreme imbalances (mostly in winter) and thus humidify the dry outside air. It doesn’t really work as a dehumidifier. Or why do they still always include an air dryer in air conditioning systems if it would be that much easier...?

Best regards,

Andreas
 

Knallkörper

2017-05-31 09:59:53
  • #3
That would probably require gigantic surface areas to enable a noticeable moisture exchange through a membrane given the vapor pressure differences. I once looked for characteristic values or curves on this, but didn't really find anything.
 

Bieber0815

2017-05-31 22:04:33
  • #4
Equilibrium, that is, equal vapor pressures on both sides, is reached with an infinitely large enthalpy exchanger (membrane area). In practice, equilibrium is of course never reached. Completely analogous to heat (temperature equalization).

I never claimed that.
 

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